1. Field of the Invention
The present invention relates to an optical information recording apparatus for use in an optical information recording medium such as optical card, optical disc and opto-magnetic disc. Particularly, the present invention relates to an optical information recording apparatus by which optical information can be recorded on the medium with high speed.
2. Description of the Related Art
In apparatuses for recording/reproducing optical information on/from optical information recording medium such as optical card, it is arranged that the optical information recording medium and an optical head are relatively moved to each other when optical information is recorded and/or reproduced on/from the optical card. Therefore, information recording speed and information reproducing speed are determined depending upon a relative moving speed of the information recording medium and the optical head. When optical information is recorded and/or reproduced only on/from a single track, it is not possible to make the information recording and/or reproducing speed high.
In U.S. Pat. No. 4,730,293, Japanese Patent Preliminarily Publications No. 2-141932 and 2-206069, and Papers C-325 of the Electric Telecommunication Society at the National Great Autumn Meeting in 1989 of "High Speed Optical Card Reader/Writer using Two Optical Sources", optical information recording/reproducing apparatuses, in which optical information can be reproduced with a high speed, are suggested. In these conventional apparatuses, in order to make the information reproducing speed high, an optical light beam is made incident upon a plurality of data tracks to read out all of the information recorded on the tracks at the same time.
In FIGS. 1 and 2, there are illustrated constructions of an optical head and an optical system for detecting data signal and tracking error signal, respectively, disclosed in the Papers C-325 of the Electric Telecommunication Society at the National Great Autumn Meeting in 1989 of "High Speed Optical Card Reader/Writer using Two Optical Sources". As shown in FIG. 1, the optical head disclosed in the Papers comprises two light sources, i.e. a laser diode 1 and a light emitting diode 2; the light beam emitted from the laser diode 1 is for use in recording information and the light beam from the light emitting diode 2 for use in reproducing information. The information recording light beam emitted from the laser diode 1 is made incident upon an optical card 6 via a collimator lens 3, a polarizing beam splitter 4 and an objective lens 5, which is arranged to be driven in focusing and tracking directions by a lens actuator 7; and the information reproducing light beam emitted from the light emitting diode 2 is made incident via the polarizing beam splitter 4 via a collimator lens 8, then reflected thereby, and the reproducing light beam is made incident upon the objective lens 5 in an off-axial condition to be introduced on the optical card 6; a reflection light beam reflected by the optical card 6 is reflected by the polarizing beam splitter 4 again; and then the reflection light beam is made incident upon a beam splitter 12 via a mirror 9, a condenser lens 10 and a mirror 11; the reflection light beam is divided into two light beams by the beam splitter 12; and then one of the divided light beams is received by a detector 13 for detecting data signal and tracking error signal and the other is by a detector 14 for detecting a focusing error signal.
In such an optical head, as shown in FIG. 2, a light beam spot 15 for reproducing information and a light beam spot 16 for recording information are formed on the optical card 6 so as to be separated from each other. It should be noted that two or more tracks are illuminated by the light beam spot 15; and an image 17 of the light beam spot 15 is formed on the detector 13 via a lens system 18 for detecting the data signal and the tracking error signal. The detector 13 comprises light receiving elements 19 and 20 for reading out information data recorded on data tracks formed on the optical card 6 and triangle-shaped light receiving elements 22 and 23, which are arranged between the light receiving regions 19 and 20, for receiving an image of a track guide 21 formed between the data tracks. Information data recorded on the data tracks is read out on the basis of outputs of the light receiving elements 19 and 20 and the tracking error signal is detected on the basis of outputs of the light receiving elements 22 and 23.
In this optical head, since two data tracks are illuminated by the light bream spot 15, information data recorded on these two data tracks can be reproduced at the same time.
Further, in the conventional apparatuses when information is recorded on the optical card 6, recorded information can be verified at the same time. That is to say, both the light beam for recording information and the light beam for reproducing information are made incident upon the optical card 6 simultaneously; and information is recorded on the data tracks by forming a data pit with the aid of the light beam having a high power, and just thereafter thus recorded information is reproduced with the aid of the light beam for reproducing information on the basis of the tracking and focusing error signals detected from the light beam for reproducing information. On the other hand, when information is reproduced from the optical card 6, only the light beam for reproducing information is made incident upon the optical card 6 to read out information recorded on the two data tracks at the same time, detecting the tracking error signal and the focusing error signal with the aid of the light beam for reproducing information.
However, in the conventional apparatus for recording/reproducing information on/from the optical information recording medium, it is possible to read out information with high speed but impossible to record information with high speed, because recording is performed by modulating a single laser diode 1 to record information on a single data track. As a solution for the slow speed problem when recording information, it can be considered to record information on a plurality of data tracks simultaneously with the aid of a plurality of laser diodes for recording. However, there would occur the problem that the optical head would become large in size and expensive in price.